Two-cycle engine



C. L. BOWDEN. Two-cYcLE ENGINE.

APPLICATION FILED MAY 28, 19l7.

Patented Jamel, 1920.

2 SHEETS-SHEET l.

A TTORNEY W1 TNESS C. L. BWDEN.

TWO-CYCLE ENGINE.

APPLICATION FILED MAY 2s, 1917.

Patented June 1,1920.-

2 SHEETS-SHEET 2- IN VEN TOR. hafe Bon/dew BY @La ATTORNEY W l TNESS UNITED STA CHARLES L. BOWDEN,

s PATENT OFFICE.

F CHICAGO, ILLINOIS.

TWO-GYCLE ENGINE.

To all whom t may concern:

Be it known that I, GHARLEs L. BoWDifT, a citizen of the United States, residing-yat Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in yTwo-Cycle Engines,

of which the following is a specification.

. My invention relates to an improved two cycle engine for use with gas or gaseous mixture which is burned in the engine cylinder and it is a purpose of my invention to overcome by my construction many of the diiiiculties which have heretofore been experienced in pperating engines of this kind.

In connection with two `cycle engines, that is to say in' which`there is a power stroke.

for each revolution of the crank shaft with a single acting engine, satisfactory results havebeensecured for conditions where the engine can run under considerable load. The engine has the advantage" over the four cycle typel of requiring but one-half the .number of cylinders for the .same power impulses in a given time and the construction is simpler in that the intake and exhaust ports may be controlled directly by the en gine piston instead ofrequiring valves and valve-operating gearing to control the intake and exhaust as is necessary in connec- 'tion with the four-cycle type of engine. It

has been found, however, under'certain conditions of operation that many diiiculties arise in operating a two cycle engine, among which may be mentioned, first, that the engine will not run smoothly on a nearly closed condition of the throttle valve on ccount of the frequent missingwhich cours, that is to say failure to fire the charge for each rotation of the crank shaft for each cylinder; second, considerable vibration of the engine when running idle appears to load up with mixture to such an Specification of Letters Patent.

Patented June 1,1920.

Application 'inea may 2s, 1917. serial No. 171,378.

extent that it is difficult to startvit. All of these difficulties and others I find" to be due to the fact that during the condition of idle running of the engine, thatis to say running with a nearly closed throttle in the intake plpe, the' engine cylinder'receives a relat1vely small amount ofexplosive mixture, which, notwithstanding the fact that it is richer than is the case when running' on fulll load owing to theusual construction and operation of the carbureter, is not. suiiicient to be fired for each working stroke of the piston. This, I find, is not due to the fact that a charge is notadm-itted o the cylinder lfor each stroke, but rather to the fact that'the charge admitted to the'cylinder is so small for idle running that it fre- "quently fails to reach the location ofthe spark plug and therefore is not in communication with the 'spark plug when the spark is formed and cannot be fired .by the spark.

When this is the case the engine misses and continues to miss until by successive strokes a sufiicient charge'is accumulated in the 'cylinder to reach the spark plug at the time of firing, for which condition an abnormally powerful explosion occurs which results in an extreme shock to the whole structure, producing vibration and noise. This condition .is the more pronounced -in view of there being practically no load on the engine when for example it is used as the power plant of an automobile and is 5 "running with the clutchout, since the engine at this time is not required to drive g'fearing of any kind, the only-load beingthat represented by the friction of the crank shaft' bearings and the parts directly connecting the crank shaft with the piston. It is believed by many that ythe engine misses because it does not scavenge properlyand that therefore the gases of combustion of a preceding' ex losion prevent the next char e being proper y fired. This I find to be te case only"because of the small quantity of fresh charge admitted to the cylinder when the engine is running with a nearly closed throttle valve. s

In my invention I provide an auxiliary .f firing chamber supplied with mixture for` each stroke of the engine through a by-pass connecting with the lntake portas a 'result of which, when the piston of the engine is in a position opening the intake port, an v auxiliary valve mechanism at the same 'time establishes communication between the said by-pass and the auxiliary firing chamber. The valve mechanism of the auxiliary chamber is preferably of the piston type and operates synchronously with the main piston .of the engine, lor nearly so, as a result of which the charge is compressed inthe auxiliary chamber at the same time that compression occurs in the cylinder and the auxiliary engine piston, the auxiliary chamber being an auxiliary cylinder, the auxil- .iary piston being provided with a connecting rod, crank and crank shaft geared to the main crank shaft in a ratio of 1 to l. The volume of the auxiliary cylinder, which is connected at'its head-end by a suitable port with the head end of the main cylinder, is such that when the engine is operating under no load and with a nearly closed throttle valve, the auxiliary 'cylinder is completely filled with fresh explosive mixture from the compression chamber for each stroke of the piston and as a result an explosion in the auxiliary cylinder is produced for each stroke of theengine since the spark plug is located in the head end of the auxiliary cylinder or immediately adjacent thereto. The firing which takes place in the auxiliary cylinder communicates through the port .referred to at its head end to the charge which is at the same time compressed in the main cylinder and the result is that for all conditions of operation an explosion or firing occurs in the engine for each workingstroke of its pistons and therefore for each rotationof the crank shaft. This `entirely eliminates the difficulty of vibration when running under no load because the missing of the engine is eliminated and, since the engine operates smoothly and quietly for the nearly closed throttle condition, there is no tendency for the operator to change the carbureter adjustment which in the past has frequently been done vin a vain attempt to make the engine operate properly under no load. Much of the difficulty in the past has resultedfrom improper adjustment of the carbureter in attempting to make thelengine operate under-ay no-load condition and v an improper adjustment of the timing apymeans for preventing back firing and for increasing the efficient operation of the engine under no load which consists in providing a divided intake port controlled by a valve'operated synchronously with the throttle valve so that, when the throttle valve is nearly closed, the intake port in effect is of much reduced cross section which results in maintainingr the velocity of the flow of the fresh mixture through the intake port for a closely throttled condition, this velocity of fiow being sulicient to prevent the occurrence of backfiring. Vith a properly timed spark, however, there is little tendency for backliring sincel the explosive mixture has sufficient time interval to be wholly consumed before the intake port is opened by the engine piston.

It will be understood that the pressure exerted upon the auxiliary' piston by the firing in the auxiliary cylinder is not lost since the two pistons are connected together as referred to above and, therefore. the auxiliary piston although of small diameter is also a power piston. By my invention I also provide means to retain fresh mixture flowing into the bypass connecting with the auxiliary cylinder so that back How of the mixture is prevented in said bypass.

My invention will best be understood by reference to the accompanying drawings showing a preferred embodiment thereof, in which- Figure 1 shows one cylinder of an engine in vertical central sectional view, part of the construction being shown in perspective to facilitate indicating the connections of the controlling valve, the portion of this figure to the right of the center line of the engine and above the broken line being taken along the line 1a in Fig. 4 while the remaining section is taken along the line 1-1 in Fig. 4,

Fig. 2 shows in a view similar to Fig. 1 an enlarged sectional view of the intake port and its controlling valve, this figure beingr taken along the line of 2-2 in Fig. 3,

. Fig. 3 is a sectional View of the parts shown in Fig. 2 taken along the line 3 3,

Fig. 4 is a plan view of a four cylinder engine constructed in vaccordance with my invention, and

Fig. 5 is a View similar to Fig. 1 showing a two-diameter piston type of. engine instead of the crank case compression type shown in Fig. l.

Similar numerals refer to similar throughout the several views.

As shown in Fig. 1. the engine consists of a power cylinder 10 in which a power piston 11 is disposed, said piston being connectparts yed by a connecting rod 12 with a crank 13 secured to a crank shaft 14 mounted in suitable bearings 15 secured in the crank case 16. The cylinder is provided with an intake port 17 and an exhaust port 18 formed through the side walls thereof near the crank end of the cylinder so that said ports are uncovered by the piston when in its outermost position as is common in twocycle engine practice. The exhaust port 18 is shown connected with an exhaust manifold 19. Theengine shown in Fig. 1 i's of lthe crank case compression type and is provided with a passageway 20 leading from the crank case to the intake port 17. 'lfhe explosive mixture is introduced into the crank case in a manner to be described by the suction of the piston 11 and the cycle of operation of the engine is similar to that of the ordinary two-cycleengine to the extent that for each rotation of the shaft .14 a charge of explosive mixture is drawn into the crankl case and at the same time a charge already communicated to the power cylinderis compressed, and during the reverse stroke of the working piston firing of the compressed charge in the cylinder takes place after which near the end of the stroke the exhaust port 18 first opens relieving the pressure on the gasesof combustionin the cylinder, immediately after which the intake -port 17 opens permitting the mixture in the crank case compressed by the stroke of the piston under consideration to flow through the passageway 20 and the intake port into the cylinder to scavenge the engine and place a fresh Working charge'in the cylinder.v

The, intake port 17 is ofnovel construction as shown more clearly in Figs. 2 and-3 in that it is divided by a plurality of plates 21 into several ports, saidjplate's extending entirely across the intake port and being conformed to constitute-a portion of the inner cylindrical surface of the cylinder. The

portion of the intake. port 17 opening into J the passageway 20 is engaged by a control- -ling valve 22 rigidly secured to a shaft 23 extending through the casing of the engine and having upon its outer end andv rigidly secured thereto an operating crank 24. The

, valve 22 by the engagement of its cylindrithe intake port is the area between the lowermost plates 21I and the bottom wall of the cal surface with a corresponding cylindrical bore across the outer end of the intake port 17 controls the-amount ofl opening of the intake port and as a result of the separating partitions 21 when the port is open but a small amount the effective cross section of intake port and in `thismanner for low pressures of,V gas in the crank case, as for example when the throttle valve of the engine is -nearly closed, a .relatively high velocity of ow of'mixture through the intake port /s maintained. For conditions of running Wheie' the throttle valve is opened further the valve 22 is in a position opening more of the intake port thus allowing'the mixture which at this time has a greater pressure in the crank case tojlow somewhatmore freely through the intake port, the purpose of the amount. this being continued until when the throttle is wide open the intake port is fully open. The plates 21are preferably of thin sheet metal and to properly support them against accidental displacement a web 29 is formed vertically across the intake port so that each of the parts of the intake port is controlled by two of the plates 21 which lie in the same horizontal plane. It will be understood that other constructions may be employed for supporting the plates 21 and limiting the amount of opening of the intake port by successive steps to accomplish the same result as above described without departing from my invention.

The crank case 16 has formed through 1ts Awall adjacent the lower end of the passageway 20 a port 30 controlled by va rotaryvalve f31 mounted upon a shaft 32 in a compartment 33 formed in the casing of the engine, which compartment is in communication with the intake manifold 34 which manifold in turnreceives its supply of explosive mixture through vthe pipe 35 containing the throttle valve 28 from a carbureter illustrated diagrammatically at 36. backing Wall 37 Aextends across the compartment 33 in engagement with the valve 31 to assist in supportmg it in proper operative position. The shaft 32-is connected with the shaft 14 by gears38' and 39 carried respectively by said shafts, the ratio of said gears being 1 to 1`, as a result`of which the port 30 is engagesone en'd of-a crank 26 opened by the valve 31 -for each up stroke of the power `piston immediately as the pis'- -ton begins its upward motion. and the port remains open until the upward stroke ofl the piston is completed so that during this linterval the piston may draw into the crank case from lthe carbureter 36 a quantity of explosive mixture detersmined by the setting of the throttle valve 28. When the throttle valve is wide open the mixture is drawn into the crank case with a minimum of resistance and as'the throttle valve is closed this resistance increases until with the throttle valve in its nearly closed positiona relatively small amount of mixture is drawn in to the `crank case for eachfupward stroke of the piston.

As iswell lmown in the art, when it is attempted to operate a two-cycle engine on a nearly closed throttle the difficulties above I pointed out are encountered and this results directly from the pressure of the mlxture in the crank case at that time being too low and all of the objectionable phenomena referred to above occur. To overcome this, I provide the following constructlon:

'At the head end of the power cylinder an extension of the casing is formed andin this extension an auxiliary cylinder 40 is constructed which is preferably parallel with the power cylinder. An auxiliary piston 41 is located in the auxiliary cylinder, this piston being 'connected by a connecting rod 42 with a crank 43 carried by the shaft 32. The head end of the auxiliary cylinder 40 is in continuous communication with the head end of the power lcylinder 10 through a communicating passageway 44 and near the crank end of the auxiliary cylinder an intake port 45 is formed which communicates by a passageway 20'l through a check valve 46 with the upper end of the passageway 20. A spark plug 47 is located preferably'on the head end of the auxiliary cylinder 40` although it may be located anywhere in the passageway 44 or if preferred, in the head end of the power cylinder 10 adjacent to the opening of the passageway 44. The auxiliary piston 41 is so connected through its crank 43 thatit moves practically synchronously with the power piston 11 although I find in practice that it is some- 'what desirable to have it lag in its operation slightly behind the power piston 11. The displacement effected by the auxiliary piston 41 is preferably so designed that the auxiliary cylinder 40l will be completely filled with fresh mixture yfor each power stroke even when the engine is running with the throttle valve 28 as nearly closed as possible to still maintain operation of the engine. In other words, for the. minimum pressure of mixture in the crank case at the instant the intake, ports 17 and 45 are opened by the pistons 11 and 41 respectively, the resultantflow of mixture through the'port 45 must be suicient to fill the auxiliary cylinder 40 and preferably to somewhatmore than fill it so as to be sure to ill the communicating passageway 44.- In this way I provide that the auxiliary cylinder which is really the firing chamber of the enl compressed in the power cylinder.

gine shall have a charge of fresh mixture in the power cylinder which are at least in part i fresh explosive mixture, is maintained practically uniform during the operation of compressing the -gases in L the cylinders. lVhen therefore the spark is projected across the electrodes of the spark plug 47, this is always done in the presence of a compressed charge of fresh mixture which is at once fired with the result that the ignition is comev municated through the passageway 44 to whatever fresh mixture may at the time be The resultant pressure produced in the cylinders operates as well upon the auxiliary piston 41 as on the power piston 11 and since the cranks 13 and 43 are at practically the same angular position and arel geared together in the ratio of 1 to 1- the pressure developed is effective on the two pistons to run the 'engine in proportion of the areas of the ends of the pistons. It is to be borne in mind that a two cycle engine running without load requires but little power to drive it, since the amount of mechanism operated by the engine for that condition is practically negligible` whereas with other types of engines in `which there are numerous valves and more or less complicated valve gear to be operated the power required to run ythe engine idle is much greater for the same size'engine. This of course accentuates the diiliculty met with in operating two cycle engines at .no load under ordinary conditions, since the quantity of explosive mixture required for this condition isv very small. With my construction. however, it is immaterial how small a charge of mixture is required to operate the engine when running light for as long as the auxiliary cylinder is constructed so as to be entirely filled with fresh mixture for each power stroke of the engine` the fresh mixture compressed in the auxiliary cylinder will be fired at each power stroke and the firing of this mixture .will ignite the compressed mixture which may in part constitute the contents of the power lcylinder although a considerable quantity 'of' burnt gases from a preceding stroke orstrokes may stifll remain in the power cylinder.

It will be observed that the auxiliary piston 41 performs the double function of admitting. a charge of fresh mixture to the fir-- ing chamber for each powerjstroke of the engine and also of maintaining practically constant the dividing line between the charge admitted to the auxiliary cylinder and the gases contained in the power cylinder during a compression stroke. While this construction is desirable I do not however. limit myself to it, as -I may employ other equivalent means for determinin the admission of the fresh charge to the firing chamber. When the throttle valve opened somewhat from the (most nearly closed position for which the engine will operate without load a greater quantity of mixture is drawn into the crank case for .each lcompression stroke of the pistons as referred to above, with the result that the pressure on/the mixture in the crank case is higher as a result of each power stroke of the engine and that therefore a larger quantity of fresh mixture will flow into the auxiliary cylinder for'this condition each time the intake port 45 is opened and that this quantity will increase until the throttle valve 28 is in its wide open position for which condition the maximum quantity of mixture will flow into the auxiliary cylinder for each str0ke.

its most nearly closed position for which the engine will operate, the amount of fresh mixture delivered to the auxiliary cylinder,

-40 for each rotation ofthe shafts 14 and 32,

is more than enough to ll the auxiliary cylinder and its passageway 44 which however is no detriment, since the excess is delivered `t0 the power cylinder to form a part of the 'charge for the next power stroke.

The engine shown in Fig,4 1 is provided with a water jacket 48 which operates in a manner we'll known in the art to prevent the engine from overheating.

As shown in Fig. 4, when my improved engine construction is used in a multi-cylinider arrangement, it lends itself readily to a type of engine desirable for automobile purposes in which the cylinders are cast in one piece. In this construction a four cylinder engine is shown, the, intake compartments of the cylinders being indicated at33 while the auxiliary cylinders are indicated at 40. It will be noted that the 'auxiliary cylinder may be convenientlylocated immediately adj acant the end of the intake compartment 33 for each cylinder as a result of which 'each crank 43 may be well supported by the bearings which in practiceare provided for the shaft 32 in the walls of the intake compartments. To facilitate showing in a'single view in Fig. 1 the construction of the in take compartment and the auxiliary cylinwhile the part below, the break is taken along the line 1 in Fig. 4. i

In the construction shown in Fig. a s1m1 In other words, for all conditions except with .the throttle valve inlar arrangement is used, with the exception vthat the engine is of the double diameter piston type. In this case the power cylinder 10a is provided with a power piston 11a `which has formed on its lower enda piston 50 communicates near its upper end with an intake passage 5l in communication with an intake manifold 52 through a puppet valve `53. The passagey 51 is in communication with an intake passage 54 leading to the cylinder 10a and the auxiliary cylinder 40a through a second puppet valve 55. 'Ihe cylinder 10a is provided with intake and exhaust ports 17 a and 18a respectively and the auxiliary cylinder is provided with an auxiliary piston 41a of substantially the same construction as shown and described in connection with Fig. 1, the only difference vbeing that the initial compression of the mixture is accomplished by means of the piston 49 instead of in the crank case 16 as shown in Fig. 1. It is-immaterial which form of initial compression isused although the two diameter piston construction is somewhat more expensive'to build and the crank case compression type of engine is entirely satisthe cylinder or'not. It will be observed that the auxiliary cylinder to contain any burnt gases after compression for any'condition of operation and as long as this takes place it is immaterial whether the power cylinder scavenges or not for conditions of light running. It is well known that carbureters of modern construction are so designed that the mixture delivered to the engine for a -nearly closed throttle condition is riche'r than delivered by the same carbureterif properly adjusted for full load condition of the throttle valve, which makes it more cer. tain that firing will occur foreach working any condition `of the throttle `valve for which the engine will operate. Again, it will be evident that since firing occurs for each working stroke it is impossible for the engine to become so loaded with rich mix- 'it is impossible with' my construction for stroke with my improved construction for ture that it vill not operate. Backfiring with two 'cycle engines operating under light load has usually been due to delaying the spark by such an amount in an attempt to make the enginelire properly on light load that an insufficient time interval is allowed for the charge to burn before the intake port is opened, as a result of which when the intake port is opened the fresh mixture in the compression` chamber is ignited. Proper operating conditions require that the spark shall be so adjusted that a suflicient time interval is afforded in which to burn the chargev in the power cylinder before the intake port is opened and since my improved construction secures uniform firing, the spark may be left in its proper position of adjustment for full load operation even when the engine is running under no load, with the result that an ample time interval is afforded for all practical conditions even with the ordinary construction of intake port.Y l My improved intake port construction, however, entirely eliminates all possibility of backfring since it is well known that backfiring cannot occur if the velocity o'f the gas How through the port is sufficiently high. By my construction I may make the velocity of the mixture flowing into the power cylinder as high as desired by subdivision of the port by means of the plates 21, since'by sodoing the effective area of the intake port is graded in a succession of steps from a cross section'sufv ficient to produce a high velocity of How into the power cylinder for theminimm charge of fresh mixture for no load condition to full opening of the port for the largest quantity of fresh mixture required tolow through the porton full load condition. The check valve 46 is provided so that the passageway 20a may remain filled with freshmixture at all times, so that the auxiliary cylinder will certainly receive a suficient charge of fresh mixture even for extreme conditions of light running of theK engine although for ordinary operating conditions I find it is unnecessary to employ said check valve.

It will be understood that my invention is not limited to any specific combustible for operating my improved engine, nor is it limited to any particular manner of introducing the-combustible into the cylinder or anyl particular manner of firing it. Any combustible and method of introducing the same and iirin it known to the art in connection with mternal combustion engines may be employed, the particular construction and operation described above in this `connection being merely one operative embodiment to illustrate the application of my invention to an internal combustion engine.

`My invention in its broad aspect consists in providing the power Acylinder of an internal combustion engine with an auxiliary firing chamber of such volume that the minifor the slowest speed at which the engine can be made' to run without load, in view of the friction and inertia of the moving parts. Furthermore, if desired,while I have shown the power cylinder and firing chamber supplied with combustible from thesame source and simultaneously controlled as to fuel supply, I may employ independent means for supplylng the firing chamber with fuel.

and controlling the quantity supplied, from the means employed to supply and control the fuel delivered to the powercylinder.

For some purposes the intake port valve 22 may be completely closed when the throttle valve 28 is in its nearly closed condition, as a result of which all of the pressure in the compression chamber is available to force the relatively small charges into the firing chamber, thus effectively and positively filling the firing chamberl for each power stroke. If desired, the rod 25 may be disconnected from the crank 24 and the valve 22 may be -independently operated, as for example on stationary engines or boat engines where the periods of idle running are infrequent.

IVhile I have shown my invention in the particular embodiments above described, it

will be understood that I do not limit `myself to these constructions, as I may employ any equivalents thereof known to the art at the time of the filing of this application without .departing from. the scope of the appended claims.

lVhat I claim is:

1. In a two cycle engine, the combination of a powercylinder having intake and exhaust ports nearits crank end, a power piston in said cylinder controlling the opening and closing ,of said ports, a compression chamber for containing explosive mixture under pressure, an auxiliary firing cylinder having at its head end an open passageway connecting withv the head end of the'pOWer cylinder, an intake passageway from sald compression chamber vto said, intake port and to the crank end of said auxiliary cylin- 'der, an Aauxiliary1 piston in saidn auxiliary cylinder for opening said intake passageway to the auxiliary cylinder during intake, and

`devices for firing the mixture in said anx-- l= 2. In a two cycle engine, the combination ofa power lcylinder'having intake qand exhaust ports near its crank end, a power piston in said cylinder controlling the opening and closing of said ports, a compression chamber for containing explosive mixture under pressure, an auxiliary firing cylinder having at its head end an open passageway connecting with the head. end of the power cylinder, an intake passageway from said compression chamber to said vintake port and to the crank end of said auxiliary cylinder, an auxiliary p iston in said auxiliary cylinder for opening said intake pasi sageway to the auxiliary cylinder during intake, and devices for firing the mixture in said auxiliary cylinder, said firing chamber being of a volume substantially iilled with explosive mixture'from said intake passageway for each cycle of the engine when running without load, a crank shaft connected with the power piston, and equalratio gear-v ing connecting said shaft and said auxiliary piston;

3. In a two cycle/engine, the combination of a power cylinder having intake and exhaust ports near its crank end, a power piston in said cylinder controlling the opening and closing of said ports, a compression chamber for containing explosive mixture under'pressure, an auxiliary firing cylinder having at its head end an open passageway connecting with the head end of the power cylinder,` an intake passageway from said compression chamber to said intake port and to the crank end of said auxiliary cylinder, an auxiliary piston in said auxiliaryl cylinder for opening said intake passageway to the auxiliary cylinder during "intake, devices for firing the mixture in said auxiliary cylinder, said firing chamber being of a volume substantially iilled with explosive mixture from said intake passageway for each cycle of the engine when running with- Vout load, a crank shaft connected with the power piston, equal ratio gearing connecting said shaft and said auxiliary piston, and

a valve for closing or opening said intake port as the engine is throttled or freely supplied withiexplosive mixture.

4. In a two cycle engine, the combination of a lpower cylinder having intake and exhaust ports near its crank end, a powerpis' ton in said cylinder controlling the opening and closing of said ports, a compression chamber for vcontaining explosive mixture under pressure, a' firing chamber connected with the head end of the power cylinder by an open passageway, an intake passageway from said compression chamber to said intake port and to said firing chamber, a valve for opening said intake passageway to the firing chamber during intake, devices for firing the \mixture in'said ring chamber,

said firing chamber being of a volume substantially filled with explosive mixture from said intake passageway for each cycle of the engaging said valve for changing the effective cross section of said intake port.

5. In a two cycle engine, the combination of a power cylinder having intake and exhaust-ports near its crank end, a power piston in said cylinder controlling the opening and closing of said ports, a'throttle valve for said engine for controlling the supply of combustible mixture thereto, a compression chamber for containing explosive mixture under pressure, a firing chamber connected with the'head end of the power cylinder by an open passageway, an intake passageway from said compression chamber to said intake port and to said firing chamber, a valve for opening said intake passageway to\the firing chamber during intake, devices for firing the mixture in said firing chamber, a valve -actuated with the vengine throttle valve for closing or .opening said intake port as the engine is throttled or freely supplied with explosive mixture, and transverse partitions in said intake port engaging said valve for changing the effective power piston, a firing chamber connected with the head end of the power cylinder by an open passageway, an intake passageway from said compression chamber to said intake port and to said firing chamber, a valve for opening said intake passageway to the firing vchamber during'intake, devices for liring the mixture in said firing chamber, said firing chamber being of a volume substantially Iilled with explosive mixture from said intake passageway for each cycle of the engine when running without load', a valve actuated with the engine throttle valve for closing or opening said intake port as the engine is throttled or freely supplied vwith explosive mixture, and transverse parof a power cylinder having intake and.ex-`

haust ports near its crank end, a power piston in said cylinder controlling the opening and closing of said ports, a throttle valve for'said engine for controlling the supply of combustible mixture thereto, a compression chamber for containing explosive mixture under pressure by the operation of said power piston, a firing chamber connected with the head end of the power cylinder by an open passageway, an intake passageway fromsaid compression chamber-to said in'- take port and to said firing chamber, a valve for opening said intake passageway to the firing chamber during intake, devices for firing the mixture in said firing chamber, a valve actuated with the engine throttle valve for closing or opening said intake port as the engine is throttled or freely supplied with explosive mixture, and transverse partitions in said intake port engaging said valve fon changing the effective cross section of said intake port.

8. .In a two cycle engine, the combination of a power cylinder having intake and exhaust portsl near its crank end, a"power piston in said cylinder controlling the opening and closlng of said ports, a compression lchamber for containing explosive mlxture under pressure, an auxiliary firing cylinder cylinder, said firing chamber being of a volhaving at its hea'd end an open passageway connecting with the head end of the power cylinder, an intake passageway from said compression chamber to said intake port and to the crank end of said auxiliary cylinder, an auxiliary piston in said auxiliary cylinder for opening `s aid intakepassageway to the auxiliary cylinder during intake, devices for firing the mixture in said auxiliary ume substantially filled Vwith explosive mixture from said intake passageway for each cycle of the -engine when running without load, a crank shaft connectedwith the power piston, equal ratio gearing connecting'said shaft and said auxiliary piston, a valve for closing or opening said intake port as the engine is throttled or freely supplied with explosive mixture, and transverse partitions in said intake port engaging said valve for changing the effective cross section of said intake port. y

9.( Ina two cycle engine, the combination of a'power cylinder having an exhaust port, a power piston in said cylinder'controlling the opening and closing of said port, an aux- "iliary cylinder in open communication with said power cylinder and having an intake port, an auxiliary piston in'said auxiliary cylinder forV controlling the opening and closing of said intake port, and meansv for firing the mixture in saidv auxiliary cylinder, 'said auxiliary cylinder being of a vol,

' ume to be filled with explosive mixture for each cycle of the engine when the engine is running at slow speed Without load, each of the opening and closing ofv said port, an aux-v iliary cylinder in open communication with said power cylinder-and having an intake port, an auxiliary piston in said auxiliary cylinder for controlling the opening and closing of said intake port, means'forvfiring the mixture in said auxiliary cylinder, said auxiliary cylinder being of a volume much smaller than the volume of said power cylinder to be filled with explosive mixture for each cycle of the engine when the engine is running at slow speed without load, a crank shaft, a connecting rod extending from said power piston to said shaft, and gearing connecting said auxiliary piston with said shaft in the ratio of one to one.

l1. In a two cycle engine, the combination of a power cylinder having an exhaust port, a power piston in said cylinder controlling the opening and closing of said port, an auxiliary cylinder in open communication with said power cylinder and having an intake port, an auxiliary piston in said auxiliary cylinder for controlling the opening and closing of saidintake port, means for firing the mixture in said auxiliary cylinder, said` auxiliary cylinderbeing of a volume much smaller than the volume of said power cylinder to be filled with explosive mixture for each cycle of' the engine when the engine is running without load, an intake passageway communicating with said intake port, and a y,check valve in said intake passageway- 12. In a two cycle engine, the combination of a power cylinder, a power piston in said cylinder, a crank shaft connected with said power piston, an auxiliary cylinder communicating with said-powercylinder, an auxiliary piston in said auxiliary cylinder, an auxiliary crank shaft connected with said auxiliary piston, a compression chamber, a rotary valve for controlling admission to said compression chamber and' gearing connecting said crank shafts and valve in the ratio of one to one, said rotary valve being mounted upon and driven by said auxiliary crank shaft.

13. In a two cycle engine, the combination of a power cylinder having intake and exhaust ports for fuel mixture and spentgases respectively, a power piston in said cylinder controlling the opening and closing of said ywith the head end of the power cylinder, an

auxiliary piston in said auxiliary cylinder,

and means for supplying'said auxiliary cyl-` inder with a minimum firing charge for no 'load running filling said auxiliary cylinder controlling the opening and closing of said ports, an auxiliary cylinder of small volume compared with the volume of the power cylinder in open but restricted communication with the head end of the power cylinder, an

yauxiliary piston in said auxiliary cylinder,

means for supplying said auxiliary cylinder with a minimum iring charge for no load running iilling said auxiliary cylinder for each cycle of the engine, saidminimum charge being much smaller than the volume of the power cylinder, an'd means in the auxiliary cylinder for iiring the charge therein.

15'. 1n a two cycle engine, the combination of a power cylinder having intake and exhaust ports for fuel mixture and spent gases respectively, a Vpower piston in said cylinder controlling the opening and closing of said ports, an auxiliarycylinder of small volume compared with the volume of the power cylinder in open but restricted communication with the head end of the power cylinder, an auxiliary piston in said auxiliary cylinder, means for supplying said auxiliary cylinder withv a minimum' firing charge for no load running I illing said auxiliary cylinder for each cycle of the engine, said minimum charge being much smaller than the volume of the power cylinder, and gearing connecting said pistons in the ratio of one to one.

16. In a two cycle engine, the combination of a powerl cylinder having intake and exhaust ports for fuel mixture and spent gases respectively, a power piston in said cylinder controlling the opening and closing of said ports, an auxiliary cylinder of small volume compared with the volume of the power cylinder in open but restricted communication with the head end of the power cylinder, an auxiliary piston in said auxiliary cylinder, means for supplying s aid` auxiliary cylinder with a minimum firing charge for no load running filling said auxiliary cylinder for each cycle of the engine, said minimum charge being much smaller than the volume of the power cylinder, a throttle valve for the engine, and a valve for closing said intake port as'said throttle valve is closed.

17. In an engine, the combinationvor` a power cylinder havingan intake port, a power piston in said cylinder, a throttle valve for controlling the supply of mixture to said cylinder, a control valve for opening or closing said intake port, and devices connecting said throttle valve'and said control valve to either open or close both said valves by the same operation.

18.` In an engine, the combination of a power cylinder having an intake port, a power piston in said cylinder, a throttle valve for controlling the supply of mixture to said cylinder, a control valve for opening or closing said intake port, devices connecting said throttle valve and said control valve to open or close both said valves by the same operation, and, transverse partitions in said intake port for changing the effective cross-sectionof said intake port by operation of said control valve.

19. In an engine, the combination of a power cylinder, a power piston in said 'cylinder, said cylinder having an exhaust port and an intake port for compressed mixture at its crank end opened and closed by said piston, a firing chamber in communication with the head end of said cylinder, a port and means in said firing chamber for firingl the mixture therein, said chamber being of small volume filled with mixture for the smallest charge of mixture for which the engine will run on no. load.

20. In an engine, the combination of a power cylinder, a power piston in said cylinder, said cylinder having an exhaust port and an intake port for compressed mixture at. its crank end opened and closed by said piston, a tiring chamber in communication with the head end of said cylinder, a port supplying said chamber with compressed mixture, a positively actuated valve for opening and closing said last named port, and means in said firing chamber for firing the mixture therein, said chamber being of small volume filled with mixture for the smallest charge of mixture for which the engine will run on no load, the communicatiqn between said cylinder and chamber being by an open passageway of smaller cross section than the cross section of said chamber.

21. In an engine, the combination oi va power cylinder, a power piston in said cylinder, said cylinder having an exhaust port and anintake port for compressed mixture at its crank end opened and closed by said piston, a firing chamber in communication with the head end of said cylinder, a port supplying said chamber with compressed mixture, a positively actuated valve for opening and closing said last named port, means in said tiring chamber for iring the mixture therein` said chamber being of small volume filled with mixture for the smallest charge of mixture for which the lsupplying said chambei' with compressed engine will run on no load, a throttle valve l for controlling the supply of mixture to a the engine, va control valve for changing the size of the intake port of the power c linder, and connections between said thrott e valve and said control valve for moving said control valve toward its closed position when said throttle valve is moved to its position producing slow speed of theengine.

22. In an engine, the combination of Aa' power cylinder, a power piston in said cylinder, said cylinder having an exhaust port and an intake port forlcompressed mixture at its crank end opened and closed by saidz piston, a firing chamber in lcommunication with the head en d of said cylinder, a port supplying said chamber with compressed mixture, a positively actuated valve for opening and closing said'last named port.

means i'n said firing chamber for iring the mixture therein, and a throttle valve for de creasing the mixture supplied to the engine to secure slow speed with no load, said chamber being of a volume filled with mix# ture for the slowest speed no-load condition of the throttle valve.

23. In an engine, the combination of `a. l

power cylinder, a power piston in said cylinder, said cylinder having an exhaust port and an intake port for compressed mixture Aat its crank end Aopened and closed by said smallest charge of mixture for which the engine will run on no load, said firing chamber extending laterally from one side of the head end of said cylinder. f

In witness whereof I hereunto subscribe my name this 21st da of Ma A. D. 1917.

. CHAR-EES L. OWDEN. 

